The present invention relates to a vehicle door latch device.
A conventional vehicle door latch device comprises an engagement unit that includes an engagement mechanism that comprises a latch that can engage with a striker of a vehicle body and a ratchet or a pawl that can engage with the latch in a synthetic-resin body fixed in a door in a first casing, and an operation unit that can switch to an unlock state in which the engagement unit can be released and to a lock state in which the engagement unit cannot be released in JP4765123B.
The door latch device in which an outside lever that rotates with an opening action of an outside handle on a door is pivotally mounted via a pivot shaft under a connection with the engagement unit of the first casing, and an outer end of the outside lever is connected to an outside handle and an inner end is connected to an operation mechanism.
In the door latch device in JP4765123B, a pivot portion of the outside lever to the first casing is exposed and an opening through which a part of the first casing under an engagement unit of the first casing communicates with an operation-unit holding part of the second casing, which causes a problem in antitheft performance.
For example, through a gap between an outer panel of the door and a door glass, theft means such as a special tool is inserted and got into a holding part for the operation mechanism through the opening. A locking means for the operation mechanism is unlocked by the theft means in an unlocking direction, and the door can be opened.
In order to prevent it and not to insert the theft means into the operation-mechanism holding portion, it is necessary to close the opening by providing a protection wall. If the protection wall is provided in the metal back member, the back member gets greater to increase its mass, so that it is not possible to make the door latch device smaller and lighter.
In order to improve antitheft performance, the outside lever is held in the first casing with exposure of a connecting portion with the outside handle only and it is considered that a connecting portion of the outside lever with the operation mechanism is covered with the first casing. In view of connection of the outside lever in the first casing, it is necessary that a pivot shaft for the outside lever is fixed to the back member by caulking.
In order to carry out caulking, a part around the pivot shaft of the first casing is opened and a caulking tool is inserted. An antitheft problem is likely to occur as well as the above also when the opening is formed in the first casing.
In the door latch device in Patent Literature 1, in order to position and connect the engagement unit to the first casing, positioning means is provided in the engagement unit and the first casing. Because the positioning means comprises an engagement portion or a projection in a metal back member behind the body and an engagement groove in which the engagement portion can engage, the engagement projection is formed in addition to the protection wall in the metal back member, so that the back member gets larger and heavier.